1. Field Of The Invention
This invention relates to a fluid storage and gas dispensing system which may be utilized to store high pressure liquid or other fluid, for dispensing of gas from the system for use in an application such as the manufacture of semiconductor products, such as semiconductor devices and materials.
2. Description of the Related Art
In a wide variety of industrial processes and applications, there is a need for a reliable source of process fluid(s).
Such process and application areas include semiconductor manufacturing, ion implantation, manufacture of flat panel displays, medical intervention and therapy, water treatment, emergency breathing equipment, welding operations, space-based delivery of liquids and gases, etc.
U.S. Pat. No. 4,744,221 issued May 17, 1988 to Karl O. Knollmueller discloses a method of storing and subsequently delivering arsine, by contacting arsine at a temperature of from about -30.degree. C. to about +30.degree. C. with a zeolite of pore size in the range of from about 5 to about 15 Angstroms to adsorb arsine on the zeolite. The arsine is subsequently dispensed by heating the zeolite to an elevated temperature of up to about 175.degree. C. for sufficient time to release the arsine from the zeolite material.
The method disclosed in the Knollmueller patent is disadvantageous in that it requires the provision of heating means for the zeolite material, to heat the zeolite to sufficient temperature to desorb the previously sorbed arsine from the zeolite in the desired quantity.
The use of a heating jacket or other means exterior to the vessel holding the arsine-bearing zeolite is problematic in that the vessel typically has a significant heat capacity, and therefore introduces a significant lag time to the dispensing operation. Further, heating of arsine causes it to decompose, resulting in the formation of hydrogen gas, which introduces an explosive hazard into the process system. Additionally, such thermally-mediated decomposition of arsine effects substantial increase in gas pressure in the process system, which may be extremely disadvantageous from the standpoint of system life and operating efficiency, as well as safety concerns.
The provision of interiorly disposed heating coil or other heating elements in the zeolite bed itself is problematic since it is difficult with such means to uniformly heat the zeolite bed to achieve the desired uniformity of arsine gas release.
The use of heated carrier gas streams passed through the bed of zeolite in its containment vessel may overcome the foregoing deficiencies, but the temperatures necessary to achieve the heated carrier gas desorption of arsine may be undesirably high or otherwise unsuitable for the end use of the arsine gas, so that cooling or other treatment is subsequently required to condition the dispensed gas for ultimate use.
U.S. Pat. No. 5,518,528 issued May 21, 1996 in the names of Glenn M. Tom and James V. McManus, describes a gas storage and dispensing system, for the storage and dispensing of gases, which overcomes the above-discussed disadvantages of the gas supply process disclosed in the Knollmueller patent. The gas storage and dispensing system of the Tom et al. patent comprises an adsorption-desorption apparatus, for storage and dispensing of a gas, e.g., a hydride gas, halide gas, organometallic Group V compound, etc. The gas storage and dispensing vessel of the Tom et al. patent reduces the pressure of stored sorbate gases by reversibly adsorbing them onto a carrier sorbent medium such as a zeolite or activated carbon material.
More specifically, such storage and dispensing system comprises: a storage and dispensing vessel constructed and arranged for holding a solid-phase physical sorbent medium, and for selectively flowing gas into and out of said vessel; a solid-phase physical sorbent medium disposed in said storage and dispensing vessel at an interior gas pressure; a sorbate gas physically adsorbed on the solid-phase physical sorbent medium; a dispensing assembly coupled in gas flow communication with the storage and dispensing vessel, and constructed and arranged to provide, exteriorly of the storage and dispensing vessel, a pressure below said interior pressure, to effect desorption of sorbate gas from the solid-phase physical sorbent medium, and gas flow of desorbed gas through the dispensing assembly; wherein the solid-phase physical sorbent medium is devoid of trace components such as water, metals, and oxidic transition metal species (e.g., oxides, sulfites and/or nitrates) which would otherwise decompose the sorbate gas in the storage and dispensing vessel.
By the elimination of such trace components from the solid-phase physical sorbent medium, the decomposition of the sorbate gas after 1 year at 25.degree. C. and interior pressure conditions is maintained at extremely low levels, e.g., so that not more than 1-5% by weight of the sorbate gas is decomposed.
The storage and dispensing vessel of the Tom et al. patent thus embodies a substantial advance in the art, relative to the prior art use of high pressure gas cylinders. Conventional high pressure gas cylinders are susceptible to leakage from damaged or malfunctioning regulator assemblies, as well as to rupture or other unwanted bulk release of gas from the cylinder if internal decomposition of the gas leads to rapid increasing interior gas pressure in the cylinder.
There is a continuing need in the art to provide improved fluid storage and delivery systems for selective dispensing of gases in a variety of end use applications.
Relative to the state of the art and the invention as described more fully hereinafter, pertinent art includes the following references: U.S. Pat. No. 3,590,860 to Stenner (a manually adjustable regulator valve for a liquid propane cartridge, including a regulator diaphragm and actuating spring assembly); U.S. Pat. No. 4,836,242 to Coffre et al. (a pressure reducer for supplying electronic grade gas, including a bellows and inlet valve, with a solid particles filter disposed between the bellows and a low pressure outlet); U.S. Pat. No. 5,230,359 to Ollivier (a diaphragm-based pressure regulator for a high pressure gas cylinder, wherein a valve is positioned in the regulator for adjustably throttling the flow of pressurized fluid); U.S. Pat. No. 3,699,998 to Baranowski, Jr. (a calibratable pressure regulator in which leaf spring fasteners are utilized to retain the regulator components in position); U.S. Pat. No. 3,791,412 to Mays (a pressure reducing valve for high pressure gas containers, including a pair of valve elements for dispensing low pressure throttled fluid); U.S. Pat. No. 3,972,346 to Wormser (pressure regulator featuring a U-ring seal poppet assembly); U.S. Pat. No. 4,793,379 to Eidsmore (button-operated valve for main shut-off and flow control of a pressurized gas cylinder, using magnetic actuation of valve components); U.S. Pat. No. 2,615,287 to Senesky (a gas pressure regulator including diaphragm and diaphragm-clamping member elements); U.S. Pat. No. 4,173,986 to Martin (pressurized gas flow control valve including pressure regulator and responsive poppet valve structure); U.S. Pat. No. 3,388,962 to Baumann et al. (pressurized gas fuel metering device including sintered metal pellet flow element); U.S. Pat. No. 1,679,826 to Jenkins (fluid pressure regulator for high pressure container, utilizing diaphragm element and gas filtering means comprising a felt strip); U.S. Pat. No. 2,354,283 to St. Clair (fluid pressure regulator for liquefied petroleum gas tanks, comprising pressure actuated diaphragm with flow restrictor structure to minimize vibration); U.S. Pat. No. 5,566,713 to Lhomer et al. (gas flow control dispensing assembly including piston-type pressure regulator and block reducer/regulator means); U.S. Pat. No. 5,645,192 to Amidzich (valve assembly for relieving excess gas pressure in a container, comprising sealing ring/spring assembly); U.S. Pat. No. 5,678,602 to Cannet et al. (gas control and dispensing assembly for a pressurized gas tank, including reducer and regulator means with indexed flowmeter valve); U.S. Pat. No. 2,793,504 to Webster (valve for pressurized fluid container including pressure reducer and regulator and spring bias closure means); U.S. Pat. No. 1,659,263 to Harris (regulator for pressurized gas cylinder including a diaphragm and anti-friction washer between diaphragm and annular seat of regulator); U.S. Pat. No. 2,047,339 to Thomas (liquefied petroleum gas storage apparatus including flow control unit and leakage prevention valve); and U.S. Pat. No. 3,994,674 to Baumann et al. (detachable burner assembly for container of pressurized liquefied combustible gas, including a regulator valve assembly).
It is accordingly an object of the present invention to provide an improved fluid storage and dispensing system for the selective dispensing of gases, which offers significant advantages in cost, ease of use, and performance characteristics.
There is a continuing need in the art to provide improved fluid storage and delivery systems for selective dispensing gases in a variety of end use applications.
Other objects and advantages of the invention will be more fully apparent from the ensuing disclosure and appended claims.